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Configuring IGMP Snooping

This chapter describes how to configure Internet Group Management Protocol (IGMP) snooping on a CiscoNX-OS device.

• Information About IGMP Snooping, page 1

• Licensing Requirements for IGMP Snooping, page 5

• Prerequisites for IGMP Snooping, page 5

• Guidelines and Limitations for IGMP Snooping, page 5

• Default Settings for IGMP Snooping, page 6

• Configuring IGMP Snooping Parameters, page 7

• Verifying IGMP Snooping Configuration, page 28

• Displaying IGMP Snooping Statistics, page 29

• Configuration Example for IGMP Snooping, page 29

• Related Documents, page 30

• Standards, page 30

• Feature History for IGMP Snooping in CLI, page 30

Information About IGMP Snooping

We recommend that you do not disable IGMP snooping on the device. If you disable IGMP snooping,you might see reduced multicast performance because of excessive false flooding within the device.

Note

IGMP snooping software examines Layer 2 IP multicast traffic within a VLAN to discover the ports whereinterested receivers reside. Using the port information, IGMP snooping can reduce bandwidth consumptionin a multiaccess LAN environment to avoid flooding the entire VLAN. IGMP snooping tracks which portsare attached to multicast-capable routers to help the routers forward IGMP membership reports. The IGMPsnooping software responds to topology change notifications. By default, IGMP snooping is enabled on thedevice.

Cisco Nexus 7000 Series NX-OS Multicast Routing Configuration Guide, Release 6.x OL-25789-03 1

This figure shows an IGMP snooping switch that sits between the host and the IGMP router. The IGMPsnooping switch snoops the IGMP membership reports and leave messages and forwards them only whennecessary to the connected IGMP routers.

Figure 1: IGMP Snooping Switch

The IGMP snooping software operates upon IGMPv1, IGMPv2, and IGMPv3 control plane packets whereLayer 3 control plane packets are intercepted and influence the Layer 2 forwarding behavior.

For more information about IGMP, see Configuring IGMP.

The Cisco NX-OS IGMP snooping software has the following proprietary features:

• Source filtering that allows forwarding of multicast packets based on destination and source IP.

• Multicast forwarding based on IP addresses rather than MAC addresses.

• Beginning with Cisco Release 5.2(1) for the Nexus 7000 Series devices, multicast forwarding alternatelybased on the MAC address

• Optimized multicast flooding (OMF) that forwards unknown traffic to routers only and performs nodata-driven state creation.

For more information about IGMP snooping, see RFC 4541.

IGMPv1 and IGMPv2Both IGMPv1 and IGMPv2 support membership report suppression, which means that if two hosts on thesame subnet want to receive multicast data for the same group, then the host that receives a member reportfrom the other host suppresses sending its report. Membership report suppression occurs for hosts that sharea port.

If no more than one host is attached to each VLAN switch port, you can configure the fast leave feature inIGMPv2. The fast leave feature does not send last member query messages to hosts. As soon as the softwarereceives an IGMP leave message, the software stops forwarding multicast data to that port.

IGMPv1 does not provide an explicit IGMP leave message, so the software must rely on the membershipmessage timeout to indicate that no hosts remain that want to receive multicast data for a particular group.

Cisco Nexus 7000 Series NX-OS Multicast Routing Configuration Guide, Release 6.x2 OL-25789-03

Configuring IGMP SnoopingIGMPv1 and IGMPv2

http://tools.ietf.org/wg/magma/draft-ietf-magma-snoop/rfc4541.txt

The software ignores the configuration of the last member query interval when you enable the fast leavefeature because it does not check for remaining hosts.

Note

IGMPv3The IGMPv3 snooping implementation on Cisco NX-OS supports full IGMPv3 snooping, which providesconstrained flooding based on the (S, G) information in the IGMPv3 reports. This source-based filteringenables the device to constrain multicast traffic to a set of ports based on the source that sends traffic to themulticast group.

By default, the software tracks hosts on each VLAN port. The explicit tracking feature provides a fast leavemechanism. Because every IGMPv3 host sends membership reports, report suppression limits the amount oftraffic that the device sends to other multicast-capable routers. When report suppression is enabled, and noIGMPv1 or IGMPv2 hosts requested the same group, the software provides proxy reporting. The proxy featurebuilds the group state frommembership reports from the downstream hosts and generates membership reportsin response to queries from upstream queriers.

Even though the IGMPv3membership reports provide a full accounting of groupmembers on a LAN segment,when the last host leaves, the software sends a membership query. You can configure the parameter lastmember query interval. If no host responds before the timeout, the software removes the group state.

IGMP Snooping QuerierWhen PIM is not enabled on an interface because the multicast traffic does not need to be routed, you mustconfigure an IGMP snooping querier to send membership queries. You define the querier in a VLAN thatcontains multicast sources and receivers but no other active querier.

The querier can be configured to use any IP address in the VLAN.

As a best practice, a unique IP address, one that is not already used by the switch interface or the HSRP VIP,should be configured so as to easily reference the querier. In a vPC configuration too, the querier IP shouldbe unique on the vPC primary and secondary.

The IP address for the querier should not be a broadcast IP, multicast IP, or 0(0.0.0.0).Note

When an IGMP snooping querier is enabled, it sends out periodic IGMP queries that trigger IGMP reportmessages from hosts that want to receive IP multicast traffic. IGMP snooping listens to these IGMP reportsto establish appropriate forwarding.

The IGMP snooping querier performs querier election as described in RFC 2236. A querier election occursin the following configurations:

•When there are multiple switch queriers configured with the same subnet on the same VLAN on differentswitches.

•When the configured switch querier is in the same subnet as with other Layer 3 SVI queriers.


Configuring IGMP SnoopingIGMPv3

Static Multicast MAC AddressBeginning with the Cisco Release 5.2(1) for the Nexus 7000 Series devices, you configure an outgoing interfacestatically for a multicast MAC address. Also, you can configure the IGMP snooping to use a MAC-basedlookup mode.

Previously, the system performs the lookup on a Layer 2 multicast table using the destination IP address ratherthan the destination MAC address. However, some applications share a single unicast cluster IP and multicastcluster MAC address. The system forwards traffic destined to the unicast cluster IP address by the last-hoprouter with the shared multicastMAC address. This action can be accomplished by assigning a static multicastMAC address for the destination IP address for the end host or cluster.

The default lookup mode remains IP, but you can configure the lookup type to MAC address-based. You canconfigure the lookup mode globally or per VLAN:

• If the VDC contains ports from only anM-Series module and the global lookup mode is set to IP, VLANscan be set to either one of the two lookup modes. But, if the global lookup mode is set to aMAC address,the operational lookup mode for all the VLANs changes to MAC-address mode.

• If the VDC contains ports from both an M-Series module and an F-Series module and if you change thelookup mode to a MAC address in any VLAN, the operation lookup mode changes for all of the VLANsto a MAC-address based. With these modules in the chassis, you have the same lookup mode globallyand for the VLANs. Similarly, if the global lookup mode is MAC-address based, the operational lookupmode for all VLAN is also MAC-address based.

Changing the lookup mode is disruptive. Multicast forwarding is not optimal until allmulticast entries are programmedwith the new lookupmode. Also, when 32 IP addressesare mapped to a single MAC address, you might see suboptimal forwarding on thedevice.

Note

IGMP Snooping with VDCs and VRFsA virtual device context (VDC) is a logical representation of a set of system resources. Within each VDC,you can define multiple virtual routing and forwarding (VRF) instances. One IGMP process can run per VDC.The IGMP process supports all VRFs in that VDC and performs the function of IGMP snooping within thatVDC.

You can use the show commands with a VRF argument to provide a context for the information displayed.The default VRF is used if no VRF argument is supplied.

For information about configuring VDCs, see the Cisco Nexus 7000 Series NX-OS Virtual Device ContextConfiguration Guide.

For information about configuring VRFs, see the Cisco Nexus 7000 Series NX-OS Unicast RoutingConfiguration Guide.


Configuring IGMP SnoopingStatic Multicast MAC Address

IGMP Snooping across VPLS DomainsBeginning with Cisco Release 6.2(2) for the Nexus 7000 Series devices, IGMP snooping can be configuredacross Virtual Private LAN Service (VPLS) domains. The IGMP Snooping across VPLS Domains featureenables snooping of the IGMP packets on the pseudowire and on the Layer 2 side of the network for optimaldelivery of the multicast packets.

A pseudowire is a point-to-point connection between pairs of Provider Edge (PE) devices. A pseudowireemulates services like Ethernet over an underlying core multiprotocol label switching (MPLS) network throughencapsulation into a common MPLS format. A pseudowire allows carriers to converge their services to anMPLS network by encapsulating services into a common MPLS format.

By snooping IGMP packets received on a link, the device sends multicast packets only to interested end points.Once an IGMP packet going over the Layer 2 link is snooped, it is passed to the control plane. The controlplane will add the link on which it was received to the multicast group. The IGMP packets coming on thepseudowire are also snooped and sent to the control plane. The control plane then adds the pseudowire to themulticast group. When a multicast packet is received, it will be sent only to the multicast group instead offlooding the VLAN.

Licensing Requirements for IGMP SnoopingLicense RequirementProduct

IGMP snooping requires no license. Any feature not included in a license package is bundledwith the Cisco NX-OS system images and is provided at no extra charge to you. For a completeexplanation of the Cisco NX-OS licensing scheme, see Cisco NX-OS Licensing Guide.

CiscoNX-OS

Prerequisites for IGMP SnoopingIGMP snooping has the following prerequisites:

• You are logged onto the device.

• You are in the correct virtual device context (VDC). A VDC is a logical representation of a set of systemresources. You can use the switchto vdc command with a VDC number.

• For global commands, you are in the correct virtual routing and forwarding (VRF) mode. The defaultconfiguration mode shown in the examples in this chapter applies to the default VRF.

Guidelines and Limitations for IGMP SnoopingIGMP snooping has the following guidelines and limitations:

• You must disable IGMP optimized multicast flooding (OMF) for IPv6 multicast networks that requiremulticast forwarding over a layer 2 network.


Configuring IGMP SnoopingIGMP Snooping across VPLS Domains

• You must disable IGMP optimized multicast forwarding on VLANs that require forwarding of IPv6packets.

• If you are configuring vPC peers, the differences in the IGMP snooping configuration options betweenthe two devices have the following results:

◦If IGMP snooping is enabled on one device but not on the other, the device on which snooping isdisabled floods all multicast traffic.

◦A difference in multicast router or static group configuration can cause traffic loss.

◦The fast leave, explicit tracking, and report suppression options can differ if they are used forforwarding traffic.

◦If a query parameter is different between the devices, one device expires the multicast state fasterwhile the other device continues to forward. This difference results in either traffic loss or forwardingfor an extended period.

◦If an IGMP snooping querier is configured on both devices, only one of themwill be active becausean IGMP snooping querier shuts down if a query is seen in the traffic.

• Youmust enable ip igmp snooping group-timeout when you use ip igmp snooping proxy general-queries.We recommend to set it to "never." If this is not done you might have multicast packet loss.

• Network applications that use unicast destination IP addresses with multicast destinationMAC addressesmight require the configuration of IGMP snooping to useMAC-based forwarding lookups on the switch.If the destination MAC address used for this kind of applications is a non-IP multicast MAC address,use themac address-table multicast command to statically configure the port membership. If thedestination MAC address is in the IP multicast range, 0100.5E00.0000 to 0100.5E7F.FFFF, use staticIGMP snooping membership entries for the corresponding Layer 3 IP multicast address to configure theport membership. For example, if the application uses destination MAC address 0100.5E01.0101,configure a static IGMP snooping membership entry for an IP multicast address that maps to that MACaddress. An example of this is ip igmp snooping static-group 239.1.1.1.

Default Settings for IGMP SnoopingThis table lists the default settings for IGMP snooping parameters.

DefaultParameters

EnabledIGMP snooping

EnabledExplicit tracking

DisabledFast leave

1 secondLast member query interval

DisabledSnooping querier

EnabledReport suppression


Configuring IGMP SnoopingDefault Settings for IGMP Snooping

DefaultParameters

EnabledLink-local groups suppression

DisabledIGMPv3 report suppression for theentire device

EnabledIGMPv3 report suppression perVLAN

Configuring IGMP Snooping Parameters

If you are familiar with the Cisco IOS CLI, be aware that the Cisco NX-OS commands for this featuremight differ from the Cisco IOS commands that you would use.

Note

You must enable IGMP snooping globally before any other commands take effect.Note

Configuring Global IGMP Snooping ParametersTo affect the operation of the IGMP snooping process globally, you can configure the optional IGMP snoopingparameters described in the following table:

DescriptionParameter

Enables IGMP snooping on the active VDC. The default is enabled.

If the global setting is disabled, all VLANs are treated asdisabled, whether they are enabled or not.

Note

IGMP snooping

Configures the size of the IGMP snooping history buffers. The defaultis small.

Event history

Configures the group membership timeout for all VLANs on the device.Group timeout

Configures link-local groups suppression on the device. The default isenabled.

Link-local groups suppression

Configures Optimized Multicast Flood (OMF) on all VLANs on thedevice. The default is enabled.

Optimise-multicast-flood

Configures IGMP snooping proxy for the device. The default is 5seconds.

Proxy


Configuring IGMP SnoopingConfiguring IGMP Snooping Parameters


Limits the membership report traffic sent to multicast-capable routerson the device. When you disable report suppression, all IGMP reportsare sent as is to multicast-capable routers. The default is enabled.

Report suppression

Configures IGMPv3 report suppression and proxy reporting on thedevice. The default is disabled.

IGMPv3 report suppression

Notes for IGMP Snooping Parameters

The following are additional notes about some of the IGMP snooping parameters.

• IGMP Snooping Proxy parameter

To decrease the burden placed on the snooping switch during each IGMP general query (GQ) interval,Cisco NX-OS provides a way to decouple the periodic general query behavior of the IGMP snoopingswitch from the query interval configured on the multicast routers.

Beginning with Cisco NX-OS release 5.2(1), a configuration option became available to enable the CiscoNexus 7000 switch to consume IGMP general queries from the multicast router, rather than floodingthe general queries to all the switchports.

When receiving a general query, the switch produces proxy reports for all currently active groups anddistributes the proxy reports over the period specified by the MRT that is specified in the router query.At the same time, independent of the periodic general query activity of the multicast router, the switchsends an IGMP general query on each port in the VLAN in a round-robin fashion. It cycles through allthe interfaces in the VLAN at the rate given by the following formula.

Rate = {number of interfaces in VLAN} * {configured MRT} * {number of VLANS}

When running queries in this mode, the default MRT value is 5,000 milliseconds (5 seconds), whichmeans that in a switch that has 500 switchports in a VLAN, it would take 2,500 seconds (40 minutes)to cycle through all the interfaces in the system. This is also true when the Cisco Nexus 7000 switchitself is the querier.

This behavior ensures that only one host responds to a general query at a given time and it keeps thesimultaneous reporting rate below the packet-per-second IGMP capability of the switch (approximately3,000 to 4,000 pps).

When using this option, you must change the ip igmp snooping group-timeoutparameter to a high value or to never time out.

Note

The ip igmp snooping proxy general-queries[mrt] command causes the snooping function to proxyreply to general queries from the multicast router, while also sending round-robin general queries oneach switchport with the specified MRT value (the default MRT value is 5 seconds).

• IGMP Snooping Group-timeout parameter

Configuring the group-timeout parameter disables the behavior of expiring membership based on threemissed general queries. The group membership remains on a given switchport until the switch receivesan explicit IGMP leave on that port.

The ip igmp snooping group-timeout {timeout|never} command modifies or disables the behavior ofan expiring IGMP snooping group membership after three missed general queries.


Configuring IGMP SnoopingConfiguring Global IGMP Snooping Parameters

Procedure

PurposeCommand or Action

Enters globalconfiguration mode.

config t

Example:switch# config tswitch(config)#

Step 1

The followingcommands can be

DescriptionOptionStep 2

Enables IGMP snooping for the device.The default is enabled.

If the global setting is disabledwith the no form of thiscommand, IGMP snooping onall VLANs is disabled, whetherIGMP snooping is enabled on aVLAN or not. If you disableIGMP snooping, Layer 2multicast frames flood to allmodules.

Note

IGMP snooping can beconfigured across VirtualPrivate LAN Service (VPLS)domains.

Note

ip igmp snoopingswitch(config)# ip igmpsnooping

used to configure theIGMP snooping.

Configures the size of the event historybuffer. The default is small.

ip igmp snooping event-history{igmp-snoop-internal | mfdm |

mfdm-sum | rib | vlan |

vlan-events | vpc} size {disabled| large | medium | small}switch(config)# ip igmpsnooping event-historyigmp-snoop-internal size large

Configures the group membershiptimeout value for all VLANs on thedevice.

ip igmp snoopinggroup-timeout{minutes|never}switch(config)# ip igmpsnooping group-timeout never

Configures link-local groups suppressionfor the entire device. The default isenabled.

ip igmp snoopinglink-local-groups-suppressionswitch(config)# ip igmpsnoopinglink-local-groups-suppression

Optimizes OMF on all VLANs on thedevice. The default is enabled.

ip igmp snoopingoptimise-multicast-floodswitch(config)# ip igmpsnoopingoptimise-multicast-flood


Configuring IGMP SnoopingConfiguring Global IGMP Snooping Parameters


DescriptionOption

Configures IGMP snooping proxy forthe device. The default is 5 seconds.

ip igmp snooping proxygeneral-queries [mrt seconds]switch(config)# ip igmpsnooping proxy general-queries

Limits the membership report traffic sentto multicast-capable routers. When youdisable report suppression, all IGMPreports are sent as is to multicast-capablerouters. The default is enabled.

ip igmp snoopingv3-report-suppressionswitch(config)# ip igmpsnooping v3-report-suppression

Configures IGMPv3 report suppressionand proxy reporting. The default isdisabled.

ip igmp snoopingreport-suppressionswitch(config)# ip igmpsnooping report-suppression

Configures the maximum number ofgeneral query misses permitted. Therange is 3 to 5 queries. The default is 3queries.

ip igmp snooping max-gq-misscountswitch(config)# ip igmpsnooping max-gq-miss 5

(Optional) Savesconfigurationchanges.

copy running-config startup-config

Example:switch(config)# copy running-config startup-config

Step 3

Configuring IGMP Snooping Parameters per VLANTo affect the operation of the IGMP snooping process per VLAN, you can configure the optional IGMPsnooping parameters described in this table.


Enables IGMP snooping on a per-VLAN basis. The default is enabled.

If the global setting is disabled, all VLANs are treated as disabled, whetherthey are enabled or not.

Note

IGMP snooping

Tracks IGMPv3 membership reports from individual hosts for each port on aper-VLAN basis. The default is enabled.

Explicit tracking

Enables the software to remove the group state when it receives an IGMP leavereport without sending an IGMP querymessage. This parameter is used for IGMPv2hosts when no more than one host is present on each VLAN port. The default isdisabled.

Fast leave


Configuring IGMP SnoopingConfiguring IGMP Snooping Parameters per VLAN


Configures the group membership timeout for the specified VLANs.Group timeout

Sets the interval that the software waits after sending an IGMP query to verify thatno hosts that want to receive a particular multicast group remain on a networksegment. If no hosts respond before the last member query interval expires, thesoftware removes the group from the associated VLAN port. Values range from 1to 25 seconds. The default is 1 second.

Last member queryinterval

Configures Optimized Multicast Flood (OMF) on specified VLANs. The defaultis enabled.

Optimise-multicast-flood

Configures IGMP snooping proxy for the specifiedVLANs. The default is 5 seconds.Proxy

Configures a snooping querier on an interface when you do not enable PIM becausemulticast traffic does not need to be routed. You can also configure the followingvalues for the snooping querier:

• timeout—Timeout value for IGMPv2

• interval—Time between query transmissions

• maximum response time—MRT for query messages

• startup count—Number of queries sent at startup

• startup interval—Interval between queries at startup

Snooping querier

Configures the robustness value for the specified VLANs.Robustness variable

Limits the membership report traffic sent to multicast-capable routers on aper-VLAN basis. When you disable report suppression, all IGMP reports are sentas is to multicast-capable routers. The default is enabled.

Report suppression

Configures a static connection to a multicast router. The interface to the router mustbe in the selected VLAN.

Multicast router

Configures a Layer 2 port of a VLAN as a static member of a multicast group.Static group

Configures link-local groups suppression on a per-VLAN basis. The default isenabled.

Link-local groupssuppression

Configures IGMPv3 report suppression and proxy reporting on a per-VLAN basis.The default is enabled per VLAN.

IGMPv3 reportsuppression

Configures the IGMP version number for the specified VLANs.

You must configure access-group (policy filter), for this command tofunction correctly.

Note

Version



Beginning with Cisco Release 5.1(1), step 3 in the following procedure changed from vlan to vlanconfiguration vlan-id. You configure the IP IGMP snooping parameters that you want by using thisconfiguration mode; however, the configurations apply only after you specifically create the specifiedVLAN. See the Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide for informationon creating VLANs.

Note

Procedure


Enters globalconfiguration mode.

configure terminal

Example:switch# configure terminalswitch(config)#

Step 1

Enables IGMPsnooping for the current

ip igmp snooping

Example:switch(config)# ip igmp snooping

Step 2

VDC. The default isenabled.

If the globalsetting isdisabled withthe no form ofthis command,IGMPsnooping on allVLANs isdisabled,whether IGMPsnooping isenabled on aVLAN or not.If you disableIGMPsnooping,Layer 2multicastframes flood toall modules.

Note

Depending on yourrelease of Cisco


Enters VLAN configuration mode.vlan vlan-idswitch(config)# vlan 2switch(config-vlan)#

NX-OS, use one of thecommands in the table.




DescriptionOption

Beginning with Cisco Release 5.1(1), usethis command to configure the IGMPsnooping parameters you want for theVLAN. These configurations do not applyuntil you create the specified VLAN.

vlan configurationvlan-idswitch(config)# vlanconfiguration 2switch(config-vlan-config)#

These commandsconfigure IGMPsnooping parameters.


EnablesIGMPsnoopingfor thecurrentVLAN.Thedefaultisenabled.

ip igmp snoopingswitch(config-vlan-config)# ip igmp snooping

TracksIGMPv3membershipreportsfromindividualhostsforeachport onaper-VLANbasis.Thedefaultisenabledon allVLANs.

ip igmp snooping explicit-trackingswitch(config-vlan-config)# ip igmp snoopingexplicit-tracking




DescriptionOption

SupportsIGMPv2hoststhatcannotbeexplicitlytrackedbecauseof thehostreportsuppressionmechanismof theIGMPv2protocol.Whenyouenablefastleave,theIGMPsoftwareassumesthat nomorethanonehost ispresentoneachVLANport.Thedefaultisdisabledfor allVLANs.

ip igmp snooping fast-leaveswitch(config-vlan-config)# ip igmp snooping fast-leave




DescriptionOption

Configuresthegroupmembershiptimeoutfor thespecifiedVLANs.

ip igmp snooping group-timeout {minutes |never}switch(config-vlan-config)# ip igmp snoopinggroup-timeout never

RemovesthegroupfromtheassociatedVLANport ifnohostsrespondto anIGMPquerymessagebeforethe lastmemberqueryintervalexpires.Valuesrangefrom 1to 25seconds.Thedefaultis 1second.

ip igmp snooping last-member-query-interval secondsswitch(config-vlan-config)# ip igmp snoopinglast-member-query-interval 3




DescriptionOption

OptimizesOMFonselectedVLANs.Thedefaultisenabled.

ip igmp snooping optimise-multicast-floodswitch(config-vlan-config)# ip igmp snoopingoptimise-multicast-flood

ConfiguresanIGMPsnoopingproxyforspecifiedVLANs.Thedefaultis 5seconds.

ip igmp snooping proxy general-queries mrt secondsswitch(config-vlan-config)# ip igmp snooping proxygeneral-queries




DescriptionOption

Configuresasnoopingquerierwhenyou donotenablePIMbecausemulticasttrafficdoesnotneedto berouted.The IPaddressis usedas thesourceinmessages.

ip igmp snooping querier ip-addressswitch(config-vlan-config)# ip igmp snooping querier172.20.52.106




DescriptionOption

ConfiguresasnoopingqueriertimeoutvalueforIGMPv2whenyou donotenablePIMbecausemulticasttrafficdoesnotneedto berouted.Thedefaultis 255seconds.

ip igmp snooping querier-timeout secondsswitch(config-vlan-config)# ip igmp snoopingquerier-timeout 300




DescriptionOption

Configuresasnoopingqueryintervalwhenyou donotenablePIMbecausemulticasttrafficdoesnotneedto berouted.Thedefaultvalueis 125seconds.

ip igmp snooping query-interval secondsswitch(config-vlan-config)# ip igmp snoopingquery-interval 120




DescriptionOption

ConfiguresasnoopingMRTforquerymessageswhenyou donotenablePIMbecausemulticasttrafficdoesnotneedto berouted.Thedefaultvalueis 10seconds.

ip igmp snooping query-max-response-time secondsswitch(config-vlan-config)# ip igmp snoopingquery-max-response-time 12




DescriptionOption

Configuressnoopingfor anumberofqueriessent atstartupwhenyou donotenablePIMbecausemulticasttrafficdoesnotneedto berouted.

ip igmp snooping startup-query-count valueswitch(config-vlan-config)# ip igmp snoopingstartup-query-count 5

Configuresasnoopingqueryintervalatstartupwhenyou donotenablePIMbecausemulticasttrafficdoesnotneedto berouted.

ip igmp snooping startup-query-interval secondsswitch(config-vlan-config)# ip igmp snoopingstartup-query-interval 15000




DescriptionOption

Configurestherobustnessvaluefor thespecifiedVLANs.Thedefaultvalueis 2.

ip igmp snooping robustness-variable valueswitch(config-vlan-config)# ip igmp snoopingrobustness-variable 5

Limitsthemembershipreporttrafficsent tomulticast-capablerouters.Whenyoudisablereportsuppression,allIGMPreportsaresent asis tomulticast-capablerouters.Thedefaultisenabled.

ip igmp snooping report-suppressionswitch(config-vlan-config)# ip igmp snoopingreport-suppression




DescriptionOption

Configuresa staticconnectionto amulticastrouter.Theinterfaceto theroutermustbe intheselectedVLAN.Youcanspecifytheinterfaceby thetypeandthenumber,suchasethernetslot/port.

ip igmp snooping mrouter interface interfaceswitch(config-vlan-config)# ip igmp snoopingmrouter interface ethernet 2/1




DescriptionOption

ConfiguresaLayer2 portof aVLANas astaticmemberof amulticastgroup.Youcanspecifytheinterfaceby thetypeandthenumber,suchasethernetslot/port.

ip igmp snooping static-group [group-ip-addr ]source[source-ip-addr] interface interfaceswitch(config-vlan-config)# ip igmp snooping static-group

230.0.0.1 interface ethernet 2/1

Configureslink-localgroupssuppressionfor thespecifiedVLANs.Thedefaultisenabled.

ip igmp snooping link-local-groups-suppressionswitch(config-vlan-config)# ip igmp snoopinglink-local-groups-suppression




DescriptionOption

ConfiguresIGMPv3reportsuppressionandproxyreportingfor thespecifiedVLANs.ThedefaultisenabledperVLAN.

ip igmp snooping v3-report-suppressionswitch(config-vlan-config)# ip igmp snoopingv3-report-suppression

ConfigurestheIGMPversionnumberfor thespecifiedVLANs.

Youmustconfigureaccess-group(policyfilter),for thiscommandtofunctioncorrectly.

Note

ip igmp snooping version valueswitch(config-vlan-config)# ip igmp snooping version 2

(Optional) Savesconfiguration changes.


Example:switch(config)# copy running-config startup-config

Step 5



Changing the Lookup ModeBeginning with Cisco Release 5.2(1) for the Nexus 7000 Series chassis, you can configure the lookup modeto be based on the MAC address either globally or per VLAN.

Procedure


Enters global configuration mode.config t


Step 1

Globally changes the lookupmode to be based on theMACaddress. To return to the default IP lookup mode, use theno form of this command.

layer-2 multicast lookup mac

Example:

Step 2

After layer-2multicast lookupmac is configured,the Cisco Nexus 7000 device still floods unicasttraffic with multicast MAC address under thefollowing conditions:

Note

• Both ingress and egress ports are on one ofthe three modules: M1, M2 or M3.

• Both ingress and egress ports are layer 2ports (e.g. either an access port or a trunkport) in two different VLANs. Cisco Nexus7000 device provides routing between thetwo VLANs.

• The destination IP address is a NLBmulticast/IGMP host. In other words, thedestination IP is unicast and the destinationMAC address starts with 0100.5E.

switch(config)# layer-2multicast lookup mac

Changes the lookupmode to be based on theMAC addressfor the specified VLANs. To return to the default IP lookupmode for these VLANs, use the no form of this command.

vlan vlan-id

Example:

Step 3

switch(config)# vlan 5switch(config-vlan)#layer-2 multicast lookup mac

switch(config-vlan)# layer-2multicast lookup macswitch(config-vlan)#


Configuring IGMP SnoopingChanging the Lookup Mode


Exits configuration and/or VLAN configuration mode.exit

Example:switch(config)# exitswitch#

Step 4

(Optional) Displays the IGMP snooping lookup mode.show ip igmp snooping lookup-modevlan [vlan-id]

Step 5

Example:

switch# show ip igmp snoopinglookup-mode

(Optional) Copies the running configuration to the startupconfiguration.


Example:switch# copy running-configstartup-config

Step 6

Configuring a Static Multicast MAC AddressBeginning with Cisco Release 5.2(1) for the Nexus 7000 Series chassis, you can configure an outgoing interfacestatically for a multicast MAC address.

Procedure


Enters global configuration mode.config t


Step 1

Configures the specified outgoing interfacestatically for a multicast MAC address.

mac address-table multicast multicast-mac-addrvlan vlan-id interface slot/port

Example:

Step 2

switch(config)# mac address-table multicast01:00:5f:00:00:00 vlan 5 interfaceethernet 2/5


Configuring IGMP SnoopingConfiguring a Static Multicast MAC Address


Exits configuration and/or VLANconfiguration mode.

exit

Example:

switch(config)# exitswitch#

Step 3

(Optional) Displays the IGMP snoopingstatic MAC addresses.

show ip igmp snooping mac-oif [detail | vlanvlan-id [detail]]

Example:

switch# show feature-set

Step 4

(Optional) Copies the running configurationto the startup configuration.


Example:

switch# copy running-config startup-config

Step 5

Verifying IGMP Snooping ConfigurationTo display the IGMP configuration information, perform one of the following tasks:


Displays the IGMP snooping configuration byVLAN.show ip igmp snooping [vlan vlan-id]

Displays IGMP snooping information about groupsby VLAN.

show ip igmp snooping groups [source [group] |group | [source] | [ vlan vlan-id] [detail]

Displays IGMP snooping queriers by VLAN.show ip igmp snooping querier [ vlan vlan-id]

Displays multicast router ports by VLAN.show ip igmp snooping mroute [ vlan vlan-id]

Displays IGMP snooping explicit tracking informationby VLAN.

show ip igmp snooping explicit-tracking [ vlanvlan-id]

Displays the IGMP snooping lookup mode.show ip igmp snooping lookup-mode [ vlan vlan-id]

Displays IGMP snooping static MAC addresses.show ip igmp snooping mac-oif [ detail | vlanvlan-id[ detail]]

Displays VLANs, which have pseudowire interfacesthat are operationally up.

show ip igmp snooping pw vlan brief


Configuring IGMP SnoopingVerifying IGMP Snooping Configuration

Displaying IGMP Snooping StatisticsUse the show ip igmp snooping statistics vlan command to display IGMP snooping statistics. You can seethe virtual port channel (vPC) statistics in this output.

Use the clear ip igmp snooping statistics vlan command to clear IGMP snooping statistics.

For detailed information about using these commands, see the Cisco Nexus 7000 Series NX-OS MulticastRouting Command Reference.

Configuration Example for IGMP SnoopingThis example shows how to configure the IGMP snooping parameters:

switch# config tswitch# ip igmp snoopingswitch# vlan 2switch# ip igmp snoopingswitch# ip igmp snooping explicit-trackingswitch# ip igmp snooping fast-leaveswitch# ip igmp snooping last-member-query-interval 3switch# ip igmp snooping querier 172.20.52.106switch# ip igmp snooping report-suppressionswitch# ip igmp snooping mrouter interface ethernet 2/1switch# ip igmp snooping static-group 230.0.0.1 interface ethernet 2/1switch# ip igmp snooping link-local-groups-suppressionswitch# ip igmp snooping v3-report-suppression

This example shows how to configure the IGMP snooping parameters beginning with Cisco Release 5.1(1):

switch# config tswitch# ip igmp snoopingswitch# vlan configuration 2switch# ip igmp snoopingswitch# ip igmp snooping explicit-trackingswitch# ip igmp snooping fast-leaveswitch# ip igmp snooping last-member-query-interval 3switch# ip igmp snooping querier 172.20.52.106switch# ip igmp snooping report-suppressionswitch# ip igmp snooping mrouter interface ethernet 2/1switch# ip igmp snooping static-group 230.0.0.1 interface ethernet 2/1switch# ip igmp snooping link-local-groups-suppressionswitch# ip igmp snooping v3-report-suppression

The following example shows how to configure IGMP Snooping across VPLS Domains:switch# configure terminalswitch(config)# ip igmp snoopingswitch(config)# ip igmp snooping event-history igmp-snoop-internal size largeswitch(config)# ip igmp snooping group-timeout neverswitch(config)# ip igmp snooping link-local-groups-suppressionswitch(config)# ip igmp snooping optimise-multicast-floodswitch(config)# ip igmp snooping proxy general-queriesswitch(config)# ip igmp snooping report-suppressionswitch(config)# ip igmp snooping v3-report-suppression

These configurations do not apply until you specifically create the VLAN. See the Cisco Nexus 7000 SeriesNX-OS Layer 2 Switching Configuration Guide for information on creating VLANs.


Configuring IGMP SnoopingDisplaying IGMP Snooping Statistics

Related DocumentsDocument TitleRelated Topic

Cisco Nexus 7000 Series NX-OS Virtual Device ContextConfiguration Guide

VDCs

Cisco Nexus 7000 Series NX-OS Multicast RoutingCommand Reference

CLI commands

StandardsTitleStandards

—No new or modified standards are supported bythis feature, and support for existing standardshas not been modified by this feature.

Feature History for IGMP Snooping in CLIFeature InformationReleasesFeature Name

Command added to allow you to configure themaximum number of general query missespermitted.

6.2(2)ip igmp snooping max-gq-miss count

The IGMP Snooping across VPLSDomains featureenables snooping of the IGMP packets on thepseudowire as well as on the Layer 2 side of thenetwork for optimal delivery of the multicastpackets.

The following command was introduced:

show ip igmp snooping pw vlan brief

6.2(2)IGMP Snooping across VPLS domains

You can configure IGMP snooping to use theforwarding lookup mode as MAC-based, as well asassign a static MAC address.

5.2(1)Configuring lookup mode to MAC andassigning a static MAC address

Command added to allow you to configure a VLANbefore you actually create the VLAN.

5.1(1)vlan configuration vlan-id


Configuring IGMP SnoopingRelated Documents

Feature InformationReleasesFeature Name

List of guidelines and limitations that apply to avPC.

Display vPC statistics with the show ip igmpsnooping statistics vlan command.

The following sections provide information aboutthis feature:

• Guidelines and Limitations for IGMPSnooping

• Displaying IGMP Snooping Statistics

4.1(3)vPC


Configuring IGMP SnoopingFeature History for IGMP Snooping in CLI


Configuring IGMP SnoopingFeature History for IGMP Snooping in CLI